Relief Valve Sizing for Vessels Containing Solids

[apatjr]

The thermal expansion calculations for pressure vessels are based on an empty vessel. If the empty vessel is in a fire and the gas stored starts to expand rapidly the relief valve will protect the vessel from damage.

However, what if the vessel is filled with a solid like desiccant in a heatless dryer. The desiccant pellets will occupy some of the internal space and reduce the volume of gas stored in the vessel.

Is there a correction factor that is applied to the relief valve orifice calculation to allow for the reduction in internal volume?

Thanks in advance for any thoughts.

 

[vpl]

Remember the ideal gas law?

Patricia Lougheed

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[chicopee]

For your first remark, it is very unlikely that a properly rated safety valve ( installed on fired and unfired pressure vessels) would protect a vessel from an external fire because they are not normally rated for a fire scenario.
For your second remark, a properly sized safety valve is rated based on its energy input (BTU/HR, LBM/hr) at a particular set pressure. It is independent of its volume but having said that it is possible that energy input may be proportional to size (volume) of vessel.